1. Field of the Invention
The invention relates to a satellite, in particular a telecommunication satellite, intended to be placed in a geostationary orbit, and comprising a structure having a north face and a south face oriented perpendicularly to the rotation axis of the Earth and an east face and a west face that are periodically exposed to solar radiation as the satellite orbits the Earth, said structure supporting equipment dissipating heat, the north, south, east and west faces constituting radiator panels that radiate the heat dissipated by the equipment into space.
2. Description of the Prior Art
Telecommunication satellites are used to transmit diverse signals (audio, video, data, etc.) from one point on the globe to another. They carry a payload consisting primarily of electronic equipment that dissipates excess heat that must be rejected into the surrounding vacuum by radiation.
It is conventional to use the N/S faces as radiator panels to dissipate the excess heat, because these panels are at the lowest temperatures. Because of the equatorial orbit of the satellite, the solar energy is at a minimum on the N/S faces, whereas the other four faces are exposed directly to solar radiation during a portion of the orbit of the satellite around the Earth. The N/S panels can be thermally coupled to reduce temperature fluctuations and improve heat rejection.
However, as there is a requirement to increase the payload of new generation satellites, the capacity of the N/S panels is no longer sufficient. It is for this reason that attempts have been made to increase the heat rejection capacity.
To this end, U.S. Pat. No. 6,073,887 (Loral Inc.) proposes using the E/W faces as radiator panels in addition to the N/S panels. As these faces are exposed to strong variations of solar radiation during an orbit of the satellite around the Earth, the above document teaches coupling them thermally by means of heat pipes to reduce the temperature variations, which can be further reduced by feeding heat to the points at the lowest temperatures by simultaneously coupling the east/west/Earth/anti-Earth faces by means of looped heat pipes. Equipment is mounted directly on the east and west faces and possibly also on the Earth and anti-Earth faces.
In a system of the above type, the temperature of the equipment depends directly on the temperature of the radiator panels with which it is in contact, so that it is necessary to dedicate a greater or lesser proportion of the heat rejection capacity of the satellite to cooling the panels exposed to solar radiation. This reduces the rejection capacity available for the equipment. Furthermore, it is necessary to heat the radiator panels at certain times, to reduce the equipment temperature variations, and this increases the average operating temperature of the equipment.